Process for preparing water repellent cotton textiles and the product

ABSTRACT

Cotton and other cellulosic textiles have been reacted with hexafluoroisopropyl acrylate (6FIPA) in a free-radicalinitiated graft-copolymerization process to form durable cellulosiccopolymer products which have imparted water repellency and find utility in rainwear, tents, awnings, sails and the like goods. The imparted water repellency is durable to laundering and normal weathering.

United States Patent [191 Mares et al.

[ 1 Oct.14, 1975 PROCESS FOR PREPARING WATER REPELLENT CO'ITON TEXTILESAND THE PRODUCT [76] Inventors: Trinidad Mares, 6416 Cummins St.,Metairie, La. 70003; Jett C. Arthur, Jr., 3013 Ridgeway Drive, Metairie,La. 70002 [22] Filed: Jan. 31, 1973 21 Appl. No: 328,198

[56] References Cited UNITED STATES PATENTS 3,504,000 3/1970 Pittman etal 8/1 16 R 3,606,993 9/1971 Arthur et al. 8/1 16 R 3,698,856 10/1972Pittman et al 8/116 R Primary Examiner-Stephen J. Lechert, Jr.

[ ABSTRACT Cotton and other cellulosic textiles have been reacted withhexafluoroisopropyl acrylate (6F1PA) in a freeradicalinitiatedgraft-copolymerization process to form durable cellulosic-copolymerproducts which have imparted water repellency and find utility inrainwear, tents, awnings, sails and the like goods. The imparted waterrepellency is durable to laundering and normal weathering.

2Claims, N0 Drawings PROCESS FUR PREPARING WATER REPELLENT COTTONTEXTILES AND-THE PRODUCT A non-exclusive, irrevocable,"rQyaItyfreelicense in the invention herein described, throughout the world forall purposes of the United States Government, with the power to grantsublicenses for such purposes, is hereby granted to the Government ofthe United States of America. g

This invention relates to a process for imparting to cotton and othercellulosic textiles the quality of water repellency. More specifically,this invention relates to a chemical process comprising the use ofirradiation of the cellulosic textile with a radioactive source to forma free radical, then reacting with hexafltioroiso propyl acrylate toform a graft copolymerwith water 'repel-.

lency properties. Obviously, these cellulosic textiles find utility inthe garment industry for use in rain wear, tents, awnings, sails, etc.The imparted water repellency has been found durable to weathering aswell as ordinary laundering. I

. H HEXAFLUOROISOPROPYLA FgC-C-CF,

ACRYLATE l (6F1PA) (I) i c=cH 1-1 The uses of cotton in both personaland industrial out-of-dooruses have been limited due to the low degreeof water repellency of the cotton textile products. Usually, the waterrepellency properties of cotton textile products have been improved byweaving of heavier and more densely or tightly fitted cotton fabrics orby coating cotton fabric, which is normally woven, with materials whichhave water repellent properties. Weaving of a heavier and more denselyor tightlyfitted cotton fabric greatly increases the cost of the textileproduct thereby restricting its usage to only high cost items. Coatingof less expensive cotton fabrics, which are normally woven, with waterrepellent materials gives products with limited uses due to the oftendrastic reduction in desired natural textile properties, such asbreaking and tearing strengths, and to the loss of the coating materialduring normal usage, thereby limiting the duration of time of usefulvalue of coated cotton products which retain water repellent properties.

The instant invention defines a distinct improvement in the textileproperties of water repellent cotton textiles, in both printcloth andsateen fabrics, by reaction of. radiation-activated cotton fabrics withhexa- .sociation of Textile ,Chemists andColOl l'ists for spray ratings,on a scale from O to 100, is greaterthan that for unmodified cottonfabrics which norrrially have spray ratings of O. The water repellencyofthe cotton copolymer fabrics is further increased when they areheatedor cured at elevated temperatures. Wehave alsoifoun d thatcottoncopolymer-fabrics prepated by the method of this invention retaina high percentage .of desirable natural properties of cotton fabrics andin many cases,

proved as compared with the desirable natural properties of unmodifiedcotton fabrics. For example, we have found by the method of thisinvention that the flex and flat abrasion resistance of the cottoncopolymer fabrics are as good-as, or in most cases, better than those ofunmodified cotton fabrics. The breaking strenghts of the cottoncopolymer fabrics are equal to or greater than the breaking strengths ofunmodified cotton fabrics. I The tearing strengths of the cottoncopolymer fabrics are about percent or greater of those properties ofunmodified cotton fabrics. The instant invention therefore defines adistinct improvement in permanently adding the property of waterrepellency to cotton textile fabrics with little or no loss of, and inmost cases,

improvement of the desirable natural textile properties of cottonfabrics.

Samples of cotton fabrics used were either printcloth (about 3.4 ouncesper square yard, 84 X 77 thread count) or sateen (about 7.5 ounces persquare yard) and were commercial grey cloths which had beenenzymatically desized, alkali scoured, and peroxide bleached on a pilotplant scale. Samples of the cotton fabrics were dried overnight at 50Cto a moisture contentof about 0.5% and then irradiated with cobalt-6Ogamma radiation to a dosage of about one megarad at ambient temperature(about 25C) in a nitrogen atmosphere in sealed glass tubes therebyproducing longlived free radicals on the cellulose molecules of-cotton.

Radiation-activated cotton fabric (about 1 part) was immersed at 25C ina solution (about 6 parts) of hexafluoroisopropyl acrylate (about 9volume-%),-methanol (about 73 volume-%), and water (about 18 volumewhichhad been purged with nitrogen for the reaction time to give the desiredpoly(hexafluoroisopropyl acrylate) add-on. After the desired reactiontime, the

cotton copolymer fabrics were washed with water, extracted with asolution of methanol (about by volume) and water (about 20% by volume)to remove the unreacted material, again washed with water, and thenair-dried at 25C. The grafted poly(hexafluoroisopropyl acrylate) add-onof the cotton copolymer fabric was determined as the increase in weightof the cotton copolymer fabric over that of unmodified cotton fabric.Typical reaction times and percentages of poly(hexafluoroisopropylacrylate) add-ons of the cotton copolymer sateen fabrics are as follows:15 minutes, 6%; 60 minutes, 11%; minutes, 17%; minutes, 22%; minutes,28%; and 240 minutes, 32%. For cotton copolymer printcloth fabrics, atypical reaction time is 8 hours for 57-58% add-0n.

The graft copolymer fabrics prepared by the process of this inventionwere evaluated in this manner. The

water repellency was determined by spray ratings of AATCC Method22-1967; breaking strength was determined by ASTM Method D 1682-64;tearing strength was determined was ASTM Method D 1424-63; and flex andflat abrasion resistance were determined respectively by Paragraph 14and 7 of ASTM Method D 1175-6.

In preliminary investigation it was determined that a quantity ofoil-repellency was noted in some of the treated fabric samples but itwas felt that further experimentation would be required.

The following examples are provided to facilitate the comprehension ofthe invention and should not be construed as limiting the invention inany manner whatsoever.

EXAMPLES To illustrate the effect of add-on of the graft copolymerssamples were selected from two groups of fabrics, sateen and printclothsamples. The selected samples of grafted poly(hexafluoroisopropylacrylate) include add-ons of to 58%. Example 1 of the tabulated data wasincluded for comparative purposes. These selected samples are presentedspecifically to illustrate the effects of the chemical modification withrespect to physical properties.

These copolymers were prepared by first activating the cotton cellulosewith about l megarad of cobalt 60 gamma radiation, then reacting theactivated cellulose at room temperature (about 25C) and controlling thedegree of reaction by varying the time. The hexafluoroisopropyl acrylate(6F1PA) was reacted in methanol: water, 80:20 volume ratios. It wasnecessary in some instances to vary the concentration as well as thetime in order to achieve the desired degree of add-on.

Attention is called to the increases in breaking strength when comparingthe reacted samples with the untreated sample, Example l. Flex and flatabrasion is worthy of note in this comparative tabulation as well as aquantity of water repellency, for examples in Examples 2, 3, and 4.Examples and 6 illustrate the effect of curing at 160 for 5 minutes toyield spray ratings of 90 and 80, these rating indicating good waterrepellency imparted by the reaction. Obviously, a lighter weight fabric,as illustrated by the printcloth samples, responds favorably to theprocess (see Examples 8, 9, and l0).

was formed with properties as shown in Example No. 3. The copolymerfabric had a water repellency of (spray rating), breaking strength of 97pounds, tearing strength of 5900 grams, and flex and flat abrasionresistances of 1.5 and 1.4, respectively, as compared with values forunmodified cotton sateen cloth fabric, Example No. 1.

By the method as described in the specification above, cotton copolymersateen cloth fabric containing poly(hexafluoroisopropyl acrylate) add-onof 25% was formed and then cured at 160C for 5 minutes, Example No. 5.The cured, copolymer fabric, Example No. 5, had a water repellency of 90(spray rating), as compared with a water repellency of 0 (spray rating)for unmodified cotton sateen cloth fabric, Example No. 1.

By the method as described in the specification above, cotton copolymersateen cloth fabric, containing poly(hexafluoroisopropyl acrylate)add-on of 30% was formed and then cured at 160C for 5 minutes, ExampleNo. 6. The cured, copolymer fabric, Example Textile and Water-RepellentProperties of Cotton-Poly(1-lexafluoroisopropyl Acrylate) CopolymerFabrics Grafted Example Polymer Breaking Tearing Resistance' SprayRating' No. Add-on Strength Strength Not 71 lb. g. Flex Flat CuredCured" Sateen Cotton Fabrics 1 O 88 0 1.0 1.0 0 2 11 88 6050 1.6 1.2 503 22 97 5900 1.5 1.4 50 4 28 101 5300 0.9 1.4 50 5 25 90 6 30 80Printcloth Cotton Fabrics "Untrcated. control cotton fabric equal 1.0.Water-repellency rated on scale from 0 to 100. "Cured at 160C for 5minutes.

By the method as described in the specification above, cotton copolymersateen cloth fabric, containing poly(hexafluoroisopropyl acrylate)add-on of 1 1%, was formed with properties as shown in Example No. 2.The copolymer fabric had a water repellency of 50 (spray rating),breaking strength of 88 pounds, tearing strength of 6050 grams, and flexand flat abrasion resistances of 1.6 and 1.2, respectively, as comparedwith values for unmodified cotton sateen cloth fabric, Example No. l, of0% add-on, 0 spray rating, 88 pounds breaking strength, 6300 gramstearing strength, and 1.0 for both flex and flat abrasion resistances.

By the method as described in the specification above, cotton copolymersateen cloth fabric, contain ing poly(hexafluoroisopropyl acrylate)add-on of 22% No. 6, had a water repellency of (spray rating), ascompared with a water repellency of 0 (spray rating) for unmodifiedcotton sateen cloth fabric, Example No. 1.

By the method as described in the specification above, cotton copolymerprintcloth, containing poly(hexafluoroisopropyl acrylate) add-on of 27%,was formed and then cured at C for 5 minutes, Example No. 8. The curedcopolymer fabric, Example No. 8, had a water repellency of 80 (sprayrating), as compared with a water repellency of 0 (spray rating) forunmodified cotton printcloth fabric, Example No. 7.

By the method as described in the specification above, cotton copolymerprintcloth fabric, containing poly( hexafluoroisopropyl acrylate) add-onof 33%, was

formed and then cured at 160C for 5 minutes, Example No. 9. The curedcopolymer fabric, Example No. 9, had a water repellency of 90 (sprayrating), as compared with a water repellency of O (spray rating) forunmodified cotton printcloth fabric, Example No. 7.

By the method as described in the specification above, cotton copolymerprintcloth fabric, containing ply(hexafluoroisopropyl acrylate) add-onof 57% was formed, Example No. 10. The copolymer fabric, Example No. 10,had a water repellency of 70 (spray rating), as compared with a waterrepellency of 0 (spray rating) for unmodified cotton printcloth fabric,Example No. 7.

By the method as described in the specification above, cotton copolymerprintcloth fabric, containing poly(hexafluoroisopropyl acrylate) add-onof 58%, was formed, Example No. 11. The copolymer fabric, Example No.11, had a breaking strength of 36 pounds, tearing strength of 560 grams,and flex abrasion resistance of 1.7, as compared with values forunmodified cotton printcloth fabric, Example No. 7, of 37 poundsbreaking strength, 770 grams tearing strength, and 1.0 flex abrasionresistance.

We claim:

1. A process for imparting to cotton and other cellulosic textiles thedesirable property of water repellency, while retaining the desirablenatural properties of cotton and other cellulosic textiles, bypreparation of cotton-poly(hexafluoroisopropyl acrylate) copolymerprintcloth or sateen fabrics, the process comprising:

a. drying the cellulosic textile to a moisture content of about 0.5%,

b. irradiating the dry cellulosic textile with a radioactitive source,in an inert atmosphere, to a dosage of l megarad,

c. immersing the irradiated cellulosic textile in a solution computed tocontain proportionately, including the cellulosic textile, about 1.0part by weight of cellulosic textile and 6.0 parts by weight ofsolution, containing hexafluoroisopropyl acrylate (about 9 volume-%),methanol (about 73 volumeand water (about 18 volume-%) at roomtemperature for periods of about 15 minutes to 8 hours to give a polymeradd-on of about from 11 weight percent to about 58 weight percent basedon the weight of the untreated textile, and

cl. washing the unreacted material off the treated cellulosic textilewith a solution of methanol (about volume-%) and water (about 20volume-%),

e. drying the treated and washed cellulosic textile.

2. The water repellent cellulosic textile produced by the process ofclaim 1.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 13,912,449 DATED October 14, 1975 |NVENTOR(5 3 Trinidad Mares and Jett C.Arthur, Jr.

it is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

The following statement should appear in the heading in Assignee: TheUnited States of America; as

represented by the Secretary of Agriculture.

Signed and Scaled this tenth Day Of February 1976 [SEAL] Arrest:

RUTH C. MASON I C. MARSHALL DANN Arresting Officer Commissioner(JVIIPGNHIS and Trademarks

1. A PROCESS FOR IMPARTING TO COTTON AND OTHER CELLULOSIC TEXTILES THEDESIRABLE PROPERTY OF WATER REPELLENCY, WHILE RETAINING THE DESIRABLENATURAL PROPERTIES OF COTTON AND OTHER CELLULOSIC TEXTILES, BYPREPARATION OF COTTON POLY-(HEXAFLUORISOPROPYL ACRYLATE) COPOLYMERPRINTCLOTH OR SATEEN FABRICS THE PROCESS COMPRISING A. DRYING THECELLULOSIC TEXTILE TO AMOISTURE CONTENT OF ABOUT 0.5%, B. IRRATIATINGTHE DRY CELLULOSIC TEXTILE WITH A RADIOACTIVE SOURCE, IN THE INERTATMOSPHERE, TO A DOSAGE OF 1 MEGARAD, C. IMMERSING THE IRRADICATEDCELLULOSIC EXTILE IN A SOLUTION COMPUTED TO CONTAIN PROPORTIONATELY,INCLUDING THE CELLULOSIC TEXTILE, ABOUT 1.0 PART BY WEIGHT OF CELLULOSICTEXTILE AND 6.0 PARTS BY WEIGHT OF SOLUTION, CONTAININGHEXAFLUROISOPROPY ACYLATE (ABOUT 9 VOLUME-%).METHANOL (ABOUT 73VOLUME-%, AND WATER (ABOUT 18 VOLUME-, ) AT ROOM TEMPRATURE FOR PERIODSOF ABOUTS 15 MINUTES TO 8 HOURS TO GIVE A POLYMER ADD-ON ABOUT FROM 11WEIGHT PERCENT OF ABOUT 58 WEIGHT PERCENT BASED ON THE WEIGHT OF THEUNTREATED TEXILE, AND D. WASHING THE UNREACTED MATERIAL OFF THE TREATEDCELLULOSIC TEXTILE WITH A SOLUTION OF METHANOL (ABOUT 80 VOLUME-%) ANDWATER (ABO 20 VOLUME-%)
 2. The water repellent cellulosic textileproduced by the process of claim 1.